6-heterocyclic-4-amino-1,3,4,5-tetrahydrobenz(cd)indoles and pharmaceutical use thereof

ABSTRACT

6-heterocyclic-4-amino-1,3,4,5-tetrahydrobenz[cd]indoles are provided which are useful in modifying the function of serotonin in mammals.

FIELD OF THE INVENTION

This invention relates to 6-heterocyclic-4-amino-1,3,4,5-tetrahydrobenz[cd]indoles and their use in modifying the function of serotonin in a mammal.

BACKGROUND OF THE INVENTION

Flaugh in U.S. Pat. No. 4,576,959 (issued 1986) disclosed a family of 6-substituted-4-dialkylamino-1,3,4,5-tetrahydrobenz[cd]indoles which are described as central serontin agonists. Leander in U.S. Pat. No. 4,745,126 (1988) disclosed a method for treating anxiety in humans employing a 4-substituted-1,3,4,5-tetrahydrobenz[cd]indole-6-carboxamide derivative.

European Patent Application 399,982 discloses certain heterocyclic-substituted aminotetralins. These compounds are disclosed as being serotonin agonists, partial agonists or antagonists.

It has now been found that certain 6-heterocyclic-substituted tetrahydrobenz[cd]indoles are useful in treating conditions requiring modification of the serotonin function in the body.

SUMMARY OF THE INVENTION

This invention relates to compounds of the Formula I ##STR1## wherein: R¹ is hydrogen, C₁ -C₄ alkyl, C₃ -C₄ alkenyl, cyclopropylmethyl, aryl-substituted C₁ -C₄ alkyl, --(CH₂)_(n) S(C₁ -C₄ alkyl), --C(O)R⁴, --(CH₂) _(n) C(O)NR⁵ R⁶ ;

R² is hydrogen, C₁ -C₄ alkyl, cyclopropylmethyl or C₃ -C₄ alkenyl,

R³ is hydrogen, C₁ -C₄ alkyl or an amino-blocking group;

n is 1-4;

R⁴ is hydrogen, C₁ -C₄ alkyl, C₁ -C₄ haloalkyl, C₁ -C₄ alkoxy or phenyl;

R⁵ and R⁶ are independently hydrogen, a C₁ -C₄ alkyl, or a C₅ -C₈ cycloalkyl, with the proviso that when one of R⁵ or R⁶ is a cycloalkyl the other is hydrogen;

HET is an aromatic 5- or 6-membered heterocyclic ring, said ring having from one to three heteroatoms which are the same or different and which are selected from the group consisting of sulfur, oxygen, and nitrogen with the proviso that the 6-membered heterocyclic ring can only contain carbon and nitrogen and with the further proviso that a 5-membered ring may contain no more than one oxygen or one sulfur but not both oxygen and sulfur.

The invention also provides a pharmaceutical formulation comprising a compound of Formula 1 in combination with a pharmaceutically acceptable excipient therefor.

A further embodiment of the invention is a method for effecting a biological response at the 5HT_(1A) receptor or 5HT_(1D) by administering a compound of Formula 1. Another embodiment involves a method for treating a variety of conditions in a mammal which require regulation of serotonin functions by administering a compound of Formula 1.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the term "alkyl"0 represents a straight or branched alkyl chain having the indicated number of carbon atoms. For example, "C₁ -C₄ alkyl " groups are methyl, ethyl, n-propyl, isopropyl, n-butyl, sec.-butyl, isobutyl and tert-butyl. "C₁ -C₈ alkyl" groups include those listed for C₁ -C₄ alkyl as well as n-pentyl, 2-methylbutyl, 3-methylbutyl, n-hexyl, 4-methylpentyl, n-heptyl, 3-ethylpentyl, 2-methylhexyl, 2,3-dimethylpentyl, n-octyl, 3-propylpentyl, 6-methylheptyl, and the like.

The term "C₃ -C₄ alkenyl" refers to olefinically unsaturated alkyl groups such as "CH2CH═CH2, --CH2CH2CH═CH2, --CH(CH3)CH═CH2 and the like.

The term "aryl" means an aromatic carbocyclic structure having six to ten carbon atoms. Examples of such ring structures are phenyl, naphthyl, and the like.

The term "cycloalkyl" means an aliphatic carbocyclic structure having the indicated number of carbon atoms in the ring. For example, the term "C₃ -C₇ cycloalkyl" means cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and cycloheptyl.

The term "aryl (C₁ -C₄ alkyl)" means an aryl structure joined to a C₁ -C₄ alkyl group. Examples of such groups are benzyl, phenylethyl, a-methylbenzyl, 3-phenylpropyl, a-naphthylmethyl, β-naphthylmethyl, 4-phenylbutyl, and the like. Similarly the term "aryl (C₁ -C₃ alkyl)" means an aromatic carbocyclic structure joined to a C₁ -C₃ alkyl.

The C₁ -C₈ alkyl, the aryl, the aryl (C₁ -C₄ alkyl) groups, and the aryl (C₁ -C₃ alkyl) can be substituted by one or two molecules. Typical aryl and/or alkyl substituents are C₁ -C₃ alkoxy, halo, hydroxy, C₁ -C₃ thioalkyl, nitro, and the like. Moreover, the aryl, aryl (C₁ -C₄ alkyl) and aryl (C₁ -C₃ alkyl) groups can also be substituted by a C₁ -C₃ alkyl or a trifluoromethyl group.

In the foregoing, the term "C₁ -C₃ alkyl" means any of methyl, ethyl, n-propyl, and isopropyl; the term "C₁ -C₃ alkoxy" means any of methoxy, ethoxy, n-propoxy, and isopropoxy; the term "halo" means any of fluoro, chloro, bromo, and iodo; and the term "C₁ -C₃ thioalkyl" means any of methylthio, ethylthio, n-propylthio, and isopropylthio.

Examples of substituted C₁ -C₈ alkyl are methoxymethyl, trifluoromethyl, 6-chlorohexyl, 2-bromopropyl, 2-ethoxy-4-iodobutyl, 3-hyroxypentyl, methylthiomethyl, and the like.

Examples of substituted aryl are p-bromophenyl, m-iodophenyl, p-tolyl, α-hydroxyphenyl, β-(4-hydroxy)naphthyl, n-(methylthio)phenyl, m-trifluoromethylphenyl, 2-chloro-4-methoxyphenyl, a-(5-chloro)naphthyl, and the like.

Examples of the substituted aryl (C1-C4 alkyl) are n-chlorobenzyl, o-methoxybenzyl, m-(methylthio)-a-methyl-benzyl, 3-(4'-triflouromethylphenyl)propyl, o-iodobenzyl, p-methylbenxyl, and the like.

The term "amino-blocking group" is used herein as it is frequently used in synthetic organic chemistry, to refer to a group which will prevent an amino group from participating in a reaction carried out on some other functional group of the molecule, but which can be removed from the amine when it is desired to do so. Such groups are discussed by T. W. Greene in chapter 7 of Protective Groups in Organic Synthesis, John Wiley and Sons, New York, 1981, and by J. W. Barton in chapter 2 of Protective Groups in Organic Chemistry, J. F. W. McOmie, ed., Plenum Press, New York, 1973, which are incorporated herein by reference in their entirety. Examples of such groups include benzyl and substituted benzyl such as 3,4-dimethoxybenzyl, o-nitrobenzyl, and triphenylmethyl; those of the formula --COOR where R includes such groups as methyl, ethyl, propyl, isopropyl, 2,2,2-trichloroethyl, 1-methyl-1-phenylethyl, isobutyl, t-butyl, t-amyl, vinyl, allyl, phenyl, benzyl, p-nitrobenzyl, o-nitrobenzyl, and 2,4-dichlorobenzyl; acyl groups and substituted acyl such as formyl, acetyl, chloroacetyl, dichloroacetyl, trichloroacetyl, trifluoroacetyl, benzoyl, and p-methoxybenzoyl; and other groups such as methanesulfonyl, p-toluenesulfonyl, p-bromobenzenesulfonyl, p-nitrophenylethyl, and p-toluenesulfonylaminocarboynl. Preferred amino-blocking groups are benzyl (--CH₂ C₆ H₅), acyl [C(O)R] or SiR₃ where R is C₁ -C₄ alkyl, halomethyl, or 2-halo-substituted-(C₂ -C₄ alkoxy).

The term "aromatic 5- or 6-membered heterocyclic ring" refers to a ring containing from one to three heteroatoms which can be nitrogen, oxygen or sulfur. The 5-membered heterocyclic rings can contain carbon and nitrogen atoms and up to one oxygen or one sulfur but not one of each. In 5-membered rings not containing oxygen or sulfur, one nitrogen can be substituted with either a hydrogen, C₁ -C₃ alkyl, phenyl or (C₁ -C₃ alkyl)phenyl group. The 6-membered heterocyclic rings can contain carbon and nitrogen atoms only. The 5- or 6-membered rings can have on or two of the carbon atoms in the ring substituted independently with C₁ -C₃ alkyl, halogen, OH, C₁ -C₃ alkoxy, C₁ -C₃ alkylthio, NH₂, CN or phenyl. Adjacent carbons in the heterocyclic ring may be connected with a --CH═CH--CH═CH-- bridge to form a benzo-fused ring on the heterocycle.

These aromatic 5- or 6-membered heterocyclic rings can be either substituted or unsubstituted and include furan, thiophene, thiazole, oxazole, isoxazole, isothiazole, oxadiazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, pyrrole, pyrazole, imidazole, and triazole. The heterocyclic ring can be attached to the benzene ring by any carbon in the heterocyclic ring, for example, 2- or 3-furan.

As used herein the following terms refer to the structure indicated and includes all of the structural isomers: ##STR2##

While all of the compounds of the invention are useful for the purposes taught herein, certain of the present compounds are preferred for such uses. Preferably R¹ and R² are both C₁ -C₄ alkyl, particularly n-propyl, R³ is hydrogen, and HET is one of the following isoxazole, pyrazole, pyridine, thiazole, or oxadiazole. Other preferred aspects of the present invention are noted hereinafter. ##STR3##

The compounds of the instant invention have at least one chiral center and therefore at least two stereoisomers can exist for each. A chiral center exists at position 4 of Formula 1. If a substituent group contains a chiral center, then additional stereoisomers can exist. Racemic mixtures as well as the substantially pure stereoisomers of Formula 1 are contemplated as within the scope of the present invention. By the term "substantially pure", it is meant that at least about 90 mole percent, more preferably at least about 95 mole percent and most preferably at least 98 mole percent of the desired stereoisomer is present compared to other possible stereoisomers.

The terms "R" and "S" are used herein as commonly used in organic chemistry to denote specific configuration of a chiral center. The term "R" refers to "right" and refers that configuration of a chiral center with a clockwise relationship of group priorities (highest to second lowest) when viewed along the bond toward the lowest priority group. The term "S" or "left" refers to that configuration of a chiral center with a counterclockwise relationship of group priorities (highest to second lowest) when viewed along the bond toward the lowest priority group. The priority of groups is based upon their atomic number (heaviest isotope first). A partial list of priorities and a discussion of stereo chemistry is contained in the book:The Vocabulary of Organic Chemistry, Orchin, et al., John Wiley and Sons Inc., publishers, page 126, which is incorporated herein by reference.

As set forth above, this invention includes the pharmaceutically-acceptable salts of the compounds of Formula 1. Since the compounds of this invention are amines, they are basic in nature and accordingly react with any number of inorganic and organic acids to form pharmaceutically acceptable salts such as hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, hydrobromic acid, hydroiodic acid, phosphorus acid and others, as well as salts derived from nontoxic organic acids such as aliphatic mono and dicarboxylic acids, amino acids, phenyl-substituted alkanoic acids, hydroxyalkanoic and hydroxyalkandioic acid, aromatic acids, aliphatic and aromatic sulfonic acids. Such pharmaceutically-acceptable salts thus include sulfate, pyrosulfate, bisulfate, sulfite, bisulfite, nitrate, phosphate, monohydrogenphosphate, dihydrogenphosphate, metaphosphate, pyrophosphate, chloride, bromide, iodide, acetate, propionate, caprylate, acrylate, formate, tartrate isobutyrate, caprate, heptanoate, propiolate, oxalate, malonate, succinate, suberate, sebacate, fumarate, maleate, mandelate, butyne-1,4-dioatae, hexyne-1,6-dioate, hippurate, benzoate, chlorobenzoate, methylbenzoate, phthalate, terephthalate, benzenesulfonate, toluenesulfonate, chlorobenzenesulfonate, xylenesulfonate, phenylacetate, phenylpropionate, phenylbutyrate, citrate, lactate, β-hydroxybutyrate, glycolate, malate, naphthalene-1-sulfonate, naphthalene-2-sulfonate and mesylate.

Preferred compounds of Formula 1 include the compounds in which R³ is hydrogen, R¹ and R² are both either n-propyl or methyl and HET is 3-isoxazolyl, 5-isoxazolyl, 3-isothiazolyl, 5-isothiazolyl, 2-imidazolyl or 4-imidazolyl. These compounds include the stereoisomers at position 4, i.e., racemic mixture of 4-R and 4-S as well as the substantially pure stereoisomers of each in which the configuration at position 4 is R or S.

As depicted in Scheme I, the compounds of the present invention ca be prepared by reacting a 4-amino-6-metallo-substituted tetrahydrobenz[cd]indole as represented by structure 2 with a heterocyclic compound represented by structure 4. In structure 2, M represents a metallo moiety such as lithium, magnesium, zinc, tin, mercury, boronic acid(--BO₂ H₂) and the like while Z is an amino-blocking group. When the metallo moiety is multivalent, it is normally associated with other moieties such as, for example, halo for magnesium (Grignard reagent) and alkyl groups for tin (trialkyltin). The heterocycle represented by structure 4 containing a leaving group "L", such as a chloro, bromo, or trifluoromethysulfonyl group, which can be displaced by the metallo-indole. The heterocycle can be substituted as set forth hereinabove. Alternatively, a 6-metallo-1,2,2a,3,4,5-hexahydrobenz[cd]indole 3 can be similarly reacted with a heterocyclic 4 to provide the 6-heteroaryl-1,2,2a,3,4,5-hexahydrobenz[cd]indole 5 which can then be oxidized and the blocking group Z¹ exchanged or replaced to provide the compounds of Formula 1. ##STR4##

The reaction of the metallo-indole 2 or metallo-indoline 3 and heterocycle 4 is accomplished in the presence of a palladium or nickel catalyst such as Pd[P(C₆ H₅)₃ ]₄, PdCl₂, Pd[P(C₆ H₅)₃ ]₂ Cl₂, Ni(acac)₂, NiCl₂ [P(C₆ H₅)₃ ]₂ and the like, wherein "acac" represents acetylacetonate and "C₆ H₅ " represents a phenyl group. The organometallic reagent 2 or 3 is prepared by methods commonly used in the art for such preparations, for example, the lithium or magnesium reagents can be prepared by contacting the appropriate 6-chloro-, 6-bromo- or 6-iodo-substituted tetrahydro- or hexahydro- benzindole with an organolithium reagent or magnesium metal in a solvent such as ether or tetrahydrofuran. Other organometallic derivatives can be used such as zinc, tin, mercury or boronic acid (--BO₂ H₂). The zinc, tin and mercury reagents can be prepared by reaction of the lithiated benzindole with a zinc, tin or mercury derivative such as zinc chloride, chlorotrialkylstannane, or mercuric chloride. The boronic acid derivative can be prepared by reacting the lithium reagent with trimethylborate followed by hydrolysis of the resulting boronate ester. Mercuric acetate can be contacted directly with the hexahydrobenzindole to provide the mercurated derivative.

The 1-nitrogen of the benzindole is preferably protected with a group such as triphenylmethyl (trityl), benzyl, or for the tetrahydrobenzindole only, triisopropylsilyl. These protecting groups are represented by Z in structures 2 and 3. The protecting group can be removed after the coupling reaction is accomplished to provide the 1-hydrobenzindole compound.

An alternative method of preparing the compounds of the instant invention involves contacting an organometallic reagent prepared from a heterocyclic compound with a 6-bromo or 6-iodo-4-aminobenzindole. The reaction is accomplished in the presence of a catalyst such as that used in reaction Scheme I. The metal in the organometallic derivative of the heterocycle can be lithium, magnesium (Grignard reagent), zinc, tin, mercury, or a boronic acid (--BO₂ H₂). These organometallic compounds can be prepared by standard methods, as described above for the benzindoles. Alternatively, the lithiated heterocycles can be prepared by treating a heterocycle with a strong base such as an alkyllithium or a lithium dialkylamide.

Unless otherwise indicated, in the following preparation procedures, Ra and Ra' may independently be hydrogen, C₁ -C₃ alkyl, halogen, OH O(C₁ -C₃ alkyl), S(C₁ -C₃ alkyl), NH₂, CN, or phenyl. Rb may be hydrogen, C₁ -C₃ alkyl, phenyl, or (C₁ -C₃ alkyl)phenyl. Rc may be a hydrogen or C₁ -C₃ alkyl.

In an alternative preparation procedure, compounds of the instant invention having a 5-membered heterocyclic ring in the 6-position can be prepared by the cycloaddition of a compound of the type represented in structure 8 wherein R¹ and R² are as defined above and B is an amino-protecting group or hydrogen, ##STR5## with a 1,3-dippole of the type ⁺ T=U-V⁻ in which T, U, and V can be selected from the following list of (a) through (i).

    ______________________________________                                                   T       U          V                                                 ______________________________________                                         (a)         CRa       N          CHRa                                          (b)         CRa       N          NRb                                           (c)         CRa       N          O                                             (d)         N         N          O                                             (e)         CRa       CRa'       NRb                                           (f)         CRa       CRa'       O                                             (g)         N         CRa'       CHRa                                          (h)         N         CRa'       NRb                                           (i)         N         CRa'       O                                             ______________________________________                                    

In this list Ra and Ra' are not OH or NH₂, N represents nitrogen and O represents oxygen, This cyclication provides products of the structure 10, wherein R¹ and R² are as defined above and B is an amino protecting group or hydrogen. ##STR6## The 1-nitrogen of structures 8 and 10 can be protected using standard protecting groups preferably (C₂ H₅)₂ NC(O)--, triisopropylsilyl, or benzenesulfonyl.

Alternatively, the 6-alkyne-substituted indole of structure 8 can be reacted with a dipole of the type ⁺ T--U=V⁻ in which T, U, and V are selected from the following list for (j) and (k):

    ______________________________________                                                   T          U         V                                               ______________________________________                                         (j)         CHRa         N         N                                           (k)         NRb          N         N                                           ______________________________________                                    

In this list Ra is not OH or NH₂ and N is nitrogen. This reaction provides products of structure 12, ##STR7## wherein R¹, R², Ra and B are as defined above.

Alternative procedures for preparing certain of the instant compounds are set forth hereinbelow in Schemes 2 through 18. As used in these reaction Schemes, "Ar" refers to the benz[cd]indole, which can be 1,3,4,5-tetrahydro or 1,2,2a,3,4,5-hexahydro, with the indicated substituent in the 6-position, "Me" is methyl, "Et" is ethyl, "NBS" represents n-bromosuccinimide, Ra, Rb and Rc are defined above, "MaCl" represents methanesulfonyl chloride, "Δ" represents heat, "φ" and "Ph" each represent phenyl, "DMF" represents dimethylformamide, "TMS" represents trimethylsilyl, "[O]" represents an oxidant, Lawesson's reagent is p-methoxyphenylthionophosphine sulfide dimer, "Ac" represents acetyl, "NCS" represents N-chlorosuccinimide, "DCC" represents dicyclohexylcarbodiimide, "DMS" represents dimethyl sulfide, "Im" represents 1-imidazolyl, and "[H]" represents a reductant. As set forth hereinabove, the 1-nitrogen of the benz[cd]indole is normally protected with an aminoblocking group. When Ar is tetrahydrobenz[cd]indole, the 1-blocking group is preferably triisopropylsilyl. When Ar is hexahydrobenz[cd]indole, the preferred 1-blocking group is triphenylmethyl. In the reaction schemes provided, Ar is preferably hexahydrobenz[cd]indole with the resulting 6-heteroaryl-substituted hexahydrobenz[cd]indole being oxidized to the corresponding tetrahydrobenz[cd]indole product. ##STR8##

Scheme 19 illustrates a preparation of a starting material for reaction Scheme 1. ##STR9##

In Scheme 19epoxides of Formula 16 are known to the art or can be prepared from compounds known to the art using common reagents and techniques. For example, Flaugh, et al., J. Med. Chem., 31, 1746 (1988); Nichols et al., Org. Prep. and Proc., Int., 9, 277 (1977); and Leanna et al., Tet. Lett., 30, No. 30, 3935 (1989), tech methods of preparation of various embodiments of compounds of structures 16. Those skilled in the art of organic chemistry will recognize that there are four stereoisomers of structure 16: ##STR10## Structures 16a and 16b are herein referred to collectively as the exoisomers; similarly, structures 16c and 16d are the endo-isomers. Leanna et al., supra, teach the preparation of epoxides of structures 16 which are substantially exo or substantially endo, as desired. The preferred starting material is the compound of structure 16 wherein Z is benzoyl and X is hydrogen; the most preferred starting material is the mixture of substantially the exo-isomers thereof.

Amino alcohols of structure 18 are formed by reacting an epoxide of structure 16 with an amine of formula R¹⁰ NH₂. Such amines are readily available. Opening of the epoxide ring proceeds substantially regiospecifically with the amino group at the 5-position and the hydroxyl group at the 4-position. The reaction is also stereospecific in the sense that stereoisomers of structures 18a-d are formed from, respectively, stereoisomers of structure 16a-d, ##STR11##

A stereoselective synthesis of the amino alcohol of structure 18, and hence of all the subsequent intermediates and products of Scheme 19, can be effected by using a substantially pure enantiomer of an amine of the formula R¹⁰ NH₂ wherein R¹⁰ contains at least one chiral center. The diasetereomers of the resulting amino alcohol can then be separated by a number of means known in the art, for example by chromatography or crystallization. Suitable solvents for recrystallization include those such as diethyl ether, n-butanol, and mixtures of hexane and ethyl acetate. An alternative method of achieving a stereospecific synthesis is depicted in Scheme 19 and comprises conversion of all the diastereomers of structure 18 to corresponding diasetereomers of structure 20, followed by the separation of said diasetereomers of structure 20; that alternative method is discussed below. If a stereoselective synthesis is not desired, then separation of the stereoisomers of the amino alcohol of structure 18 is not required and the amine R¹⁰ NH₂ need not be optically active.

A particularly efficient stereoselective process for a highly preferred compound of structure 18, 1-benzoyl-4-hydroxy-5-(1-phenylethyl)amino-1,2,2a,3,4,5-hexahydrobenz[cd]indole, comprises the reaction of a mixture of substantially the exo-isomers of the corresponding epoxide of structure 16or a mixture of substantially the endo-isomers of the corresponding epoxide of structure 16, with a substantially pure enantiomer of 1-phenethylamine in the solvent n-butanol and the subsequent selective crystallization of one of the two isomers of the amino alcohol. The temperature of the reaction can be from about 50° to about 150° C., preferably about 80° to about 100° C.

After the reaction is complete, as determined for example by thin layer chromatography or liquid chromatography, the desired amino alcohol is crystallized at about -20° to about 40° C.; the preferred temperature for the crystallization is about 0° to about 15° C. Therefore this process has the valuable attribute that the reaction and the separation of stereoisomers occur efficiently in a single step. By the proper selection of the epoxide isomers, exo or endo, and the enantiomer of 1-phenylethylamine, R or S, one can determine which of the stereoisomers of the compound of structure 18 precipitate from the reaction mixture.

A number of methods of forming axiridines such as those of structure 20 from amino alcohols such as those of Formula 18 are known to the art. Two examples are the use of diethyl azodicarboxylate and triphenylphosphine (O. Mitsunobu, Synthesis, January, 1981, page 1), and the use of bromine and triphenylphosphine (J. P. Freemer and P. J. Mondron, Synthesis, December, 1974page 894).

A particularly efficient alternative to the above methods involving treating a compound of structure 18 with a tertiary amine in an inert solvent followed by the addition of methanesulfonyl chloride.

The following stereoisomers of the axiridine of structure 20, 20a-d, arise respectively from the stereoisomers of structure 18a-d, with retention of configuration at any chiral center in the substituents Z, R¹⁰ or X: ##STR12## Suitable tertiary amines are those of the formula (R¹¹)₃ N, where the R¹¹ groups are independently C₁ -C₄ alkyl. Suitable solvents are chlorinated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride, and dichloroethane; aromatic hydrocarbons such as benzene, toluene, and the xylenes; and ethers such as tetrahydrofuran, diethyl ether, and methyl t-butyl ether. The reaction can be conducted at a temperature from about -35° to about 45° C. In the preferred embodiment, the amino alcohol is treated with triethylamine in methylene chloride at about -20° to about 0° C., then the reaction mixture is warmed to about 15° to about 35° C. for the completion of the reaction. If desired, the product, an axiridine of structure 20, can be crystallized form an appropriate solvent such as acetonitrile or isopropanol after an aqueous workup. In the event that Z contains at least one chiral center in substantially a single stereoconfiguration and that the aziridine of structure 20 is prepared as a mixture of stereoisomers, said stereoisomers can be separated by methods such as chromatography and crystallization, thereby providing a stereospecific synthesis of the aziridine of structure 20 and subsequent products.

The aziridine ring can be opened to form an intermediate secondary amine of structure 22. a number of methods of opening aziridines are commonly known. It is, however, crucial that the method used for opening the aziridine to form a secondary amine of structure 22 be substantially regiospecific; the aziridine must be opened to form substantially the 4-amino compound rather than the 5-amino compound. One such method is catalytic hydrogenolysis as taught by Y. Sugi and S. Mitsui, Bull. Chem. Soc. Jap., 43, pp. 1489-1496 (1970). Catalysts which are suitable are the usual hydrogenation and hydrogenolysis catalysts, such as the noble metal catalysts; the preferred catalyst is palladium. Suitable solvents include hydrocarbons such as hexanes and heptanes; aromatic hydrocarbons such as benzene, toluene, xylenes, ethylbenzene, and t-butylbenzene; alcohols such as methanol, ethanol, and isopropanol; and mixtures of solvents such as acetic acid mixed with said alcohols. The preferred solvent for preparing the compound of structure 22, wherein Z is benzoyl, X is hydrogen, and R¹⁰ is 1-phenylethyl, is a mixture of methanol and phosphoric acid or acetic acid. The source of hydrogen can be an atmosphere of elemental hydrogen supplied at a pressure of about 1 atmosphere or higher, or the source of hydrogen can be compounds which are suitable to serve as hydrogen donors in a catalytic transfer hydrogenolysis reaction, such as formic acid, hydrazine, or cyclohexene. The preferred hydrogen source is an atmosphere of hydrogen gas supplied at about 1 to about 10 atmospheres pressure. The temperature of the reaction may be from about -20° to about 80° C.; the preferred temperature for the hydrogenolysis of the aziridine wherein Z is benzoyl, X is hydrogen, and R¹⁰ is 1-phenylethyl is about -20° to about 0° C.

The conversion of compounds of structure 20 to compounds of structure 22 proceeds without disturbing the stereochemical configuration of the chiral centers at the 2a- or 4-positions of the structure 22 or of the chiral centers that may be present in any of the substituents.

If desired, the compound of structure 22 can be isolated by the usual methods such as crystallization. The secondary amine of structure 22 can be converted to a primary amine of structure 24 by a number of methods known to the art of organic chemistry, or alternatively the secondary amine itself can be isolated.

However, the preferred methods is to convert the secondary amine of structure 22 to the primary amine of structure 24 without isolating the secondary amine, but rather by simply continuing without interruption the hydrogenolysis reaction that produced the compound of structure 22. Therefore, the preferred solvent and catalyst are the same as those for the preparation of the secondary amine of structure 22. It may be desirable to conduct the hydrogenolysis of the secondary amine of structure 22 at a different temperature or a different pressure or different temperature and pressure than the hydrogenolysis of the aziridine of structure 20. For the hydrogenolysis of the preferred compound of structure 22 wherein Z is benzoyl, X is hydrogen, and R¹⁰ is 1-phenylethyl, the preferred temperature and pressure are about 50° to about 60° C. and about 1 to about 20 atmospheres. Under these conditions, the hydrogenolysis of compounds of structure 22 to compounds of structure 24 proceeds without disturbing the stereochemical configuration of the chiral center at the 4-position.

The isolation of the compound of structure 24 can be accomplished by the usual methods such as crystallization. If desired, the compound of structure 24 can be further purified, for example by recrystallization.

Of course, as those skilled in the art will recognize, variations of Scheme 10 will be desirable or necessary for certain embodiments of the invention. For example, it may be undesirable to subject a compound in which X is halo to the catalytic hydrogenolysis steps of Scheme 19 because the undesired displacement of the halogen may compete with the desired hydrogenolysis of the carbon nitrogen bonds. One alternative strategy is to postpone the halogenation until after the hydrogenolysis. Another alternative strategy is to use a milder means of reduction that would leave the halogen in place. A third alternative, useful in the instance when the halogen is to serve as a leaving group, is to perform the desired displacement of halogen before the hydrogenolysis step.

Compounds of Formula 1 can be prepared from the compound of structure 24, whether it exists as a mixture of stereoisomers or as a substantially pure enantiomer, using common reagents and methods well known in the art. A preferred intermediate to the compounds of the instant invention is the 6-bromo-derivative. Preferably Z is an aminoblocking group such as benzoyl. A preferred method of introducing the bromo substituent as the 6-position is by reaction with bromine in glacial acetic acid, buffered with sodium acetate. Amino blocking groups can be added, if desired, to the 4-amino substituent using such methods as those disclosed by Greene, supra, and Barton, supra. Alkyl groups can be added, if desired, to the 4-amino substituent using such common methods as ammonolysis of the appropriate halide as discussed by Morrison and Boyd, Chapter 22, Organic Chemistry, Third Edition, Allyn and Bacon, Boston, 1973, to provide a compound of structure 26 wherein R¹ and R² are defined hereinabove. If desired, the benzoyl group can be removed from the 1-position using know methods and optionally replaced with other amino- protecting groups. Preferably the benzoyl group represented by Z is replaced with a triphenylmethyl group in structure 28 prior to the metallating step to form structure 2. The aminoprotecting groups and alkyl groups can be added either before or after the bromination, as desired.

The 4-amino-6-bromotetrahydrobenz[cd]indole starring materials used to prepare the compounds of the invention can be readily prepared by other processes such as depicted as Reaction Scheme 2 disclosed in U.S. Pat. No. 4,576,959 of Flaugh, incorporated herein by reference in its entirety.

The compound of structure 26 can be oxidized to the tetrahydrobenz[cd]indole 28 using oxidizing agents such as manganese dioxide. The compound 28 where X is halo can be metallated as discussed hereinabove to provide the compound of structure 2.

The procedure of Scheme 19 using the 4,5-epoxide provides a convenient way to prepare the optically active isomers of the compounds of the present invention. Such isomers can also be isolated by resolving racemic mixtures. This resolution can be carried out in the presence of a resolving agent, by chromatography or by repeated crystallization. Particularly useful resolving agents are d- and 1-tartaric acids, d- and 1-ditoluoyltartaric acids, and the like.

The methods of preparation described in Schemes 2-18 provide compounds in which the heteroaromatic ring may or may not be substituted. The general reactions provided below set forth methodology for incorporating, interconverting, and removing substituents on the heteroaromatic ring. Additional methods for performing these transformations are cited in Comprehensive Organic Transformations by Richard C. Larock, VCH Publishers, Inc., New York (1989) which is incorporated herein by reference. "HET" refers to the heteroaromatic attached to the tetrahydrobenz[cd]indole at position C-6. ##STR13##

6-acyl-substituted-tetrahydrobenz[cd]indoles are preferred intermediates in the preparation of certain of the compounds of the instant invention, particularly 6-isoxazole-indoles and 6-pyrazole-indoles. The 6-acyl substituted indoles can be prepared by several routes using the 6-iodo-substituted indole of structure 30 as depicted in Scheme 20 where R¹, R² and Z are defined hereinabove. ##STR14##

In a preferred method of preparation as depicted in Scheme 20, the nitrile 32 is contacted with an organometallic reagent such as a Grignard reagent under standard conditions to provide the 6-acyl derivative 34. For this reaction Z is preferably triisopropysilyl. Alternatively, a 6-alkyne intermediate of structure 36 can be prepared and then hydrolyzed to provide the acyl derivative 38. This method provides a methylene group adjacent to the carbonyl group. In this method Z can be an amino protecting group such as benzoyl although the unprotected 1-nitrogen is preferred, i.e., Z is hydrogen. Compounds of structure 30 can be contacted with a palladium catalyst Pd(PPh₃)₄ [where Ph is phenyl] and the tin alkyne compound R¹² --C/C--Sn(CH₃)₃ wherein R¹² is a C₁ -C₇ alkyl, substituted C₁ -C₇ alkyl, aryl (C₁ -C₃ alkyl, substituted aryl (C₁ -C₃ alkyl), or C₃ -C₇ cycloalkyl. This reaction is normally conducted in a solvent such as toluene at an elevated temperature, for example at about 100° C. Typically an excess of the tin alkyne is used along with about 0.25 equivalents of the palladium compound based on compound 30. The 6-alkyne 36 is then contacted with HgSO₄ in water to provide the ketone 38. If desired the corresponding 1,2,2a,3,4,5-hexahydrobenz[cd]indole can be used in a reaction scheme similar to that of Scheme 20 followed by an oxidation step to provide structure 38. In this case the preferred blocking group for the 1-nitrogen, i.e., Z, is benzoyl or trityl.

In another preparation method depicted in Scheme 21, the 6-iodo derivative 30 can be used to prepare certain 6-acyl compounds directly. This is accomplished by contacting the 6-iodo compound with a trialkyltinalkyl complex and carbon monoxide in the presence of a palladium catalyst Pd(PPh₃)₄ [where Ph is phenyl] as described in the literature for arylhalides. [A. Schoenberg and R. F. Heck, J. Org. Chem., 39, p. 3327 (1974); and A. Schoenberg, I. Bartoletti, and R. F. Heck, J. Org. Chem., 39, p. 3318 (1974)]. Although a blocking group Z such as diethylcarbamoyl can be used for this method, the method can also be accomplished when Z is hydrogen or the blocking group can be removed to provide compounds of structure 40 where R¹, R² and R¹² are as defined above. Alternatively the corresponding indoline can be used in the sequence of Scheme 21 followed by an oxidation step to provide structure 40. ##STR15##

As those skilled in the art will recognize, variations of any of the reaction schemes, reagents and procedures discussed herein may be desirable or necessary for certain embodiments of the invention. Such variations are contemplated as within the scope of the present invention.

The following examples further illustrate the preparation of the compounds of this invention. The examples are provided for purposes of illustration only and are not to be construed as limiting the scope of the instant invention in any way.

The terms and abbreviations used in the instant examples have their normal meaning unless otherwise designated, for example, "° C." refers to degrees celsius; "N" refers to normal or normality; "mmmol" refers to millimole "g" refers to gram; "mL" means milliliter; "M" refers to molar; "min" refers to minutes; "hr" refers to hours; "NMR" refers to nuclear magnetic resonance; "IR" refers to infrared spectroscopy; "U.V." refers to ultraviolet spectroscopy; and "m.s." refers to mass spectrometry.

EXAMPLE 1 A. Preparation of (+)-1-Benzoyl-6-cyano-4-(di-n-propylamino)-1,2,2a,3,4,5-hexahydrobenz[c,d]indole

To a solution of (+)-1-benzoyl-6-bromo-4-(di-n-propylamino)hexahydrobenz[c,d]indole (5.5 g, 12.5 mmol) in DMF (100 mL) under a N₂ atmosphere was added 3.4 g (37.5 mmol) of CuCN and 7.1 g (37.5 mmol) of Cul. The reaction mixture was then stirred at 140° C. for 6 hr. The reaction mixture was poured onto ice, diluted with water, CH₂ Cl₂ added and stirred for 30 minutes. The mixture was filtered through a Celite pad and the filtrate was extracted twice with CH₂ Cl₂. The organic solution was washed twice with saturated NaCl solution. The CH₂ Cl₂ solution was dried over MgSO₄ and then evaporated to provide 4 g of a solid. Chromatography of this crude product over silica gel with 1:19 MeOH/CH₂ Cl₂ as eluent gave 3 g (62%) of product. mp=122°-124° C.

B. Preparation of (-)(2aR,4S)-1-Benzoyl-6-cyano-4-(di-n-propylamino)-1,2,2a,3,4,5-hexahydrobenz[c,d]indole

To a solution of (-)-6-bromo compound (30.0 g, 0.068 mol) in 500 ml of DMF was added CuCN (18.3 g; 0.2 mol) and Cul (38.0 g; 0.2 mol). The reaction mixture was then stirred at 140° C. for 6 hr. The reaction mixture was poured onto 4 L of water. The ppt was collected and washed several times with water. The ppt was suspended in dil NH₄ OH and slurred with ethyl acetate. The whole mixture was filtered through a celite pad. The ethyl acetate solution was separated and washed with brine solution. The ethyl acetate solution was dried (MgSO₄) and concentrated to dryness to provide 21.3 g of the (-)-6-nitrile.

C. Preparation of (+)(2aS,4R)-6-cyano counterpart of Example 1B

In a manner similar as in Example 1B above, the (+)-6-bromo compound (17.1 g, 0.039 mol) was contacted with CuCN (107.75 g; 0.12 mol) and Cul (22.8 g; 0.12 mol) in 300 ml DMF to give 11.6 of (+)-6-cyano compound.

EXAMPLE 2 Preparation of (+)-6-cyano-4-(di-n-propylamino)-1,2,2a,3,4,5-hexahydrobenz[c,d]indole

To a stirred solution of 4.8 g (0.0124 mol) of (+)-1-benzoyl-6-cyano-4-(di-n-propylamino)1,2,2a,3,4,5-hexahydrobenz[c,d]indole in 200 mL of THF cooled to -78° C. under a N₂ atmosphere was added 16 mL (0.025 mol ) of 1.6M solution of n-butyl lithium in hexane. The reaction mixture was stirred at 31 78° C. for 30 minutes and then allowed to warm to -20° C. To the reaction mixture was added 100 mL of 1HCl. The mixture was extracted once with ethyl ether. The acidic solution was made alkaline with the addition of cold 5N NaOH. The basic mixture was extracted twice with CH₂ Cl₂. The combined organic solution was washed with saturated NaCl solution. The CH₂ Cl₂ solution was dried over MgSO₄ and evaporated to provide 4 g of an oil. Chromatography of this oil over silica gel with ethyl acetate as eluent gave 3 g (85%) of product as an oil which upon standing solidified.

EXAMPLE 3 Preparation of (+)(2aS,4R)-1-trityl-6-cyano-4-(di-n-propylamino)-1,2,2a,3,4,5-hexahydrobenz[c,d]indole

To a solution of (+)(2aS,4R)-6-cyano-4-(di-n-propylamino)-1,2,2a,3,4,5-hexahydrobenz[c,d]indole (12.8 g, 0.045 mol) and triethylamine (4.5 g, 0.045 mol) in 400 mL of methylene chloride was added a solution of triphenylmethyl chloride (trityl chloride) (12.6 g, 0.045 mol) in 100 mL of methylene chloride dropwise at RT. The reaction mixture was stirred for 16 hr at RT. The reaction mixture was extracted water and cold 1N HCl. The organic solution was washed with saturated NaHCO₃ solution and with saturated brine solution. The organic layer was dried (MgSO₄) and concentrated to dryness in vacuo to give a residue. The residue was slurried with warm hexanes, cooled and filtered to remove insolubles. The filtrate was concentrated to an oil. The oil was chromatographed (silica gel, 20% ethyl acetate in hexanes) to provide 20.6 g of the (+)-trityl nitrile.

EXAMPLE 4 Preparation of (+)(2aS,4R)-6-acetyl-4-(di-n-propylamino)-1,2,2a,3,4,5-hexahydrobenz[c,d]indole

A solution of 2.4 g (4.6 mmol) (+)-1-trityl-6cyano-4-(di-n-propylamino)-1,2,2a,3,4,5-hexahydrobenz[c,d]indole in 100 mL of THF was treated with 25 mL of 2.0M methylmagensium bromied in diethyl ether. The reaction mixture was refluxed for 16 hr. The reaction mixture was cooled and excess Grignard reagent was decomposed with addition of saturated NH₄ Cl solution. The reaction mixture was extracted with ethyl acetate. The organic solution was evaporated to an oil. The oil was dissolved in 25 mL of 5N HCl and the solution was stirred at room temperature for 30 min. The acidic solution was made alkaline with the addition of excess concentrated NH₄ OH solution. The basic mixture was extracted twice with ethyl acetate. The combined organic solution was washed once with saturated NaCl solution and dried over MgSO₄. The ethyl acetate solution was evaporated to yield 1.4 g of an oil. Chromatography of this oil over silica gel with ethyl acetate as eluent gave 1.2 g (87%) product. Recrystallization from hexanes yielded 840 mg of the product (+) ketone. mp=121°-122° C.

EXAMPLE 5 Preparation of (+)-6-Acetyl-4-(di-n-propylamino)-1,2,2a,3,4,5-hexahydrobenz[c,d]indole

A solution of 0.5 g (1.8 mmol) of (+)6-cyanol-4-(di-n-propylamino)-1,2,2a,3,4,5-hexahydrobenz[c,d]indole in 75 mL of benzene was treated with 5 mL of 2.0M methylmagensium bromide in diethyl ether. The reaction mixture was refluxed for 2 days. The reaction mixture was cooled and excess Grignard reagent was decomposed with addition of saturated NH₄ Cl solution. The benzene layer was separated and washed once with saturated NaCl solution. The organic solution was evaporated to an oil. The oil was dissolved in 25 mL of 5N HCl and the solution was stirred at room temperature for 30 min. The acidic solution as made alkaline with the addition of excess concentrated NH₄ OH solution. The basic mixture was extracted twice with CH₂ Cl₂. The combined organic solution was washed once with saturated NaCl solution and dried over MgSO₄. The CH₂ Cl₂ solution was evaporated to yield 0.5 g of an oil. Chromatography of this oil over silica gel with ethyl acetate as eluent gave 0.4 g (75%) product as an oil which upon standing solidified. mp=76°-77° C.

EXAMPLE 6 Preparation of (+)(2aS,4R)-6-(2-pyrazyl)-4-(di-n-propylamino)-1,2,2a,3,4,5-hexahydrobenz[c,d]indole·2 HCl

A solution of (+)-1-triphenylmethyl-6-acetyl-4-(di-n-propylamino)-1,2,2a,3,4,5-hexahydrobenz[c,d]indole (1.67 g, 3 mmol) and 3 mL of tris(dimethylamino)methane in 50 mL of toluene was refluxed for 5 hr. The reaction was concentrated in vacuo and the residue was dissolved in 100 mL of CH₃ OH. To the CH₃ OH solution was 2 mL of 85% hydrazine and the reaction mixture was stirred at RT for 16 hours. To the reaction mixture was added 50 ml of 1N HCl and stirred for an additional 1 hr. The solution was concentrated in vacuo to remove CH₃ OH and the acidic solution was extracted with ethyl acetate. The acidic solution was separated and made alkaline with addition of excess concentrated NH₄ OH. The basic mixture was extracted with ethyl acetate. The ethyl acetate solution was washed with brine solution, dried (MgSO₄) and concentrated in vacuo provide 900 mg of an oil. The crude product was chromatographed through silica gel (flash column, ethyl acetate) to yield 700 mg of pyrazole compound. The oil was dissolved in 50 mL of CH₃ OH and 2 equivalents of 0.1N HCl was added to the solution. The solution was concentrated in vacuo and the residue was crystallized from ethanol/ethyl ether.

Yield--400 mg

mp=260 d

EXAMPLE 7 Preparation of (+)-6-(5-isoxaxolyl)-4-(di-n-propylamino)-1,2,2a,3,4,5-hexahydrobenz[c,d]indole·2 HCl

To a solution of (+)-6-acetyl-4-(di-n-propylamino)-1,2,2a,3,4,5-hexahydrobenz[c,d]indole (2.3 g, 7.7 mmol) and triethylamine (1.1 ml, 8 mmol) in 90 ml CH₂ Cl₂ under N₂ was added dropwise a solution of 2,2,2-trichloroethyl chloroformate. The reaction mixture was stirred at RT for 1 hr. The CH₂ Cl₂ solution was extracted with water and 1N HCl. The organic solution was washed with saturated NaHCO₃ solution and with brine solution. The CH₂ Cl₂ solution was dried (MgSO₄) and concentrated in vacuo to give 3.3 g of the 1-carbamylindoline.

A solution of this 1-carbamylindoline (3.3 g, 7.7 mmol) and tris(dimethylamino)-methane (5 mL) in 70 mL of toluene was stirred at reflux for 16 hr. The reaction mixture was concentrated to dryness in vacuo. The residue was dissolved in 50 mL of acetic acid and hydroxylamine hydrochloride (2.5 g, 36 mmol) was added. The reaction mixture was stirred at RT for 16 hr and then concentrated in vacuo to dryness. The residue was suspended in water and excess concentrated NH₄ OH was added to the mixture. The basic mixture was extracted with CH₂ Cl₂. The organic solution was washed with brine solution, dried (MgSO₄) and concentrated in vacuo to give 3.1 g of an oil. The crude product was chromatographed (flash column, silica gel 20% hexanes in ethyl acetate) to yield 2.0 g of (+)-1-carbamyl-6-isoxazolylindoline.

This isoxazole carbamate was dissolved in 20 mL of acetic acid and 1 g of zinc dust was added at once. The reaction mixture was stirred at RT for 4 hr. The reaction mixture was filtered through a celite pad and the filtrate was concentrated to dryness in vacuo. The residue was suspended in saturated NaHCO₃ solution and extracted with CH₂ Cl₂. The organic solution was washed with brine solution, dried (MgSO₄) and concentrated to an oil. The crude material was chromatographed (flash column, silica gel, ethyl acetate) to give 500 mg of isoxazole indoline. The product was dissolved in 50 mL of CH₃ OH and 2 equivalents of 0.1N HCl were added. The solution was concentrated to dryness and the residue was crystallized from ethanol/ethyl ether to give 85 mg of isoxazole substituted product as the dihydrochloride.

mp=226° C. d

EXAMPLE 8 Preparation of (+)(2aS,4R)-6-(3-isoxazolyl)-4-(di-n-propylamino)-1,2,2a,3,4,5-hexahydrobenz[c,d]indole·2 HCl

A solution of (+)-1-triphenylmethyl-6-acetyl-4-(di-n-propylamino)-1,2,2a,3,4,5-hexahydrobenz[c,d]indole (3.33 g, 6 mmol), 5 g hydroxylamine hydrochloride, 20 mL pyridine and 30 mL of ethanol was refluxed for 16 hr. The reaction mixture was concentrated to dryness in vacuo and the residue was dissolved in 5N HCl. The acidic mixture was extracted with ethyl acetate. The acidic solution was made alkaline with excess NH₄ OH solution and extracted with ethyl acetate. The ethyl acetate solution was washed with brine solution, dried (MgSO₄) and concentrated in vacuo to give 1.5 g of crude product which was chromatographed (flash column, silica gel, ethyl acetate) give to 1.2 g of oxime.

mp=129°-130° C.

To a solution of this oxime (1.2 g, 3.8 mmol) in 100 mL of THF cooled to -5° C. under a N₂ atmosphere was added 7.5 mL n-butyllithium (1.6 M in hexanes) dropwise with stirring. The reaction mixture was stirred with continuous cooling for 1 hr. To the reaction mixture was added 2 mL (26 mmol) of DMF at once and then stirred for 1 hr at RT. The reaction mixture was poured into 50 mL of 1N H₂ SO₄ and the acidic solution was warmed on a steam bath for 1 hr. The acidic solution was cooled, extracted with ethyl ether, and the made alkaline with excess 5N NaOH. The basic mixture was extracted with ethyl acetate. The organic was layer was washed with brine solution, dried (MgSO₄) and concentrated in vacuo to give 1 g of an oil. The oil was chromatographed (flash column, silica gel, ethyl acetate) to yield 500 mg of product as an oil. The oil was dissolved in 50 mL of CH₃ OH and 2 equivalents of 0.1N HCL was added. The solution was concentrated to dryness in vacuo and the residue was crystallized from ethanol/ethyl ether. Crystallization gave 300 mg of the dihydrochloride of the 6-isoxazolyl product.

mp=215° C. d

EXAMPLE 9 Preparation of (+)-1-benzoyl-6-[3-(5-aminothiazolyl)]-4-(di-n-propylamino)-1,2,2a,3,4,5-hexahydrobenz[c,d]indole

To a solution of (+)-6-acetyl-4-(di-n-propylamino)-1,2,2a,3,4,5-hexahydrobenz[c,d]indole (205 mg, 0.7 mmol) and triethyl amine (81 mg, 0.8 mmol) in 20 mL of CH₂ Cl₂ was added a solution of benzoyl chloride (112 mg, 0.8 mmol) in 20 mL of CH₂ Cl₂. The reaction mixture was stirred at RT for 2 hr. The reaction mixture was successively washed with water, saturated NaHCO₃ solution, brine solution and dried (MgSO₄). The organic layer was concentrated to dryness in vacuo to give 200 mg of the 1-benzoyl derivative.

A solution of this N-benzoyl compound (200 mg, 0.5 mmol) in 20 mL of acetic acid was saturated with HBr(gas). To the solution was added dropwise a solution of bromine (0.2 mL) in 5 mL of acetic acid. The reaction was stirred at RT for 30 min and then concentrated to dryness in vacuo. The residue was dissolved in 30 mL of ethanol then 500 mg of thiourea were added and the mixture refluxed for 16 hr. The reaction was concentrated to dryness in vacuo and the residue dissolved in water. The acidic solution was made alkaline with the addition of excess concentrated NH₄ OH. The basic mixture was extracted with CH₂ Cl₂. The organic solution was washed with brine solution, dried (MgSO₄) and evaporated to dryness to give 200 mg of an oil. The oil was chromatographed (flash column, silica gel, ethyl acetate) to provide 140 mg of the named 6-aminothiazolyl compound.

EXAMPLE 10 Preparation of (+)-(4R)-6-(3-isoxazolyl)]-4-(di-n-propylamino)-1,2,2a,3,4,5-hexahydrobenz[c,d]indole

A mixture of (+)6-(3-isoxazolyl)]-4-(di-n-propylamino)-1,2,2a,3,4,5-hexahydrobenz[c,d]indole (180 mg, 0.5 mmol) and 1 g of MnO₂ in 40 mL of CH₂ Cl₂ was sonicated at 50-55 KHz for 2 hr. The reaction mixture warmed to reflux during the time period. The reaction mixture was filtered through a celite pad and the filtrate was concentrated to dryness in vacuo. The residue was chromatographed (flash column, silica gel, ethyl acetate) to provide 50 mg of the isoxazole indole product as an oil.

The present compounds of Formula 1 have been found to have selective affinity for the 5HT receptors in the brain with much less affinity for other receptors. Because of their ability to selectively bind to 5HT receptors, the compounds of Formula 1 are useful in treating disease states which require alteration of 5-HT receptor function, particularly 5-HT_(1A), and/or 5HT_(1D) but without the side effects which may be associated with less selective compounds. This alteration may involve reproducing (an agonist) or inhibiting (an antagonist) the function of serotonin. These disease states include anxiety, depression, gastric acid secretion, hypertension, nausea, sexual dysfunction, cognition, senile dementia, migraine, consumptive disorders such as appetite disorders, alcoholism and smoking. The foregoing conditions are treated with a pharmaceutically effective amount of a compound of Formula 1 or a pharmaceutically acceptable salt thereof.

The term "pharmaceutically effective amount", as used herein, represents an amount of a compound of the invention which is capable of diminishing the adverse symptoms of the particular disease. The particular dose of compound administered according to this invention of course be determined by the particular circumstances surrounding the case, including the compound administered, the route of administration, the particular condition being treated, and similar considerations. The compounds can be administered by a variety of routes including the oral, rectal, transdermal, subcutaneous, intravenous, intramuscular or intranasal routes. A typical single dose for prophylactic treatment, however, will contain from about 0.01 mg/kg to about 50 mg/kg of the active compound of this invention when administered orally. Preferred oral doses will be about 0.01 to about 3.0 mg/kg, ideally about 0.01 to about 0.1 mg/kg. When a present compound is given orally it may be necessary to administer the compound more than once each day, for example about every eight hours. For IV administration by bolus, the dose will be from about 10 μg/kg to about 300 μg/kg, preferably about 20 μg/kg to about 50 μg/kg.

The compounds of the present invention are preferably formulated prior to administration. Therefore, yet another embodiment of the present invention is a pharmaceutical formulation comprising a compound of the invention and a pharmaceutically acceptable excipient therefor.

The present pharmaceutical formulations are prepared by known procedures using well known and readily available ingredients. In making the compositions of the present invention, the active ingredient will usually be mixed with an excipient, diluted by an excipient or enclosed within an excipient serving as a carrier which can be in the form of a capsule, sachet, paper or other container. When the excipient serves as a diluent, it can be a solid, semisolid or liquid material which acts as a vehicle, carrier or medium for the active ingredient. Thus, the compositions can be in the form of tablets, pills, powders, lozenges, sachets, aerosols (as a solid or in a liquid medium), ointments containing for example up to 10% by weight of the active compound, soft and hard gelatin capsules, suppositories, sterile injectable solutions and sterile packaged powders.

Some examples of suitable excipients include lactose, dextrose, sucrose, sorbitol, mannitol, starches, gum acacia, calcium phosphate, alginates, tragacanth, gelatin, calcium silicate, microcrystalline cellulose, polyvinylpyrrolidone, cellulose, water, syrup, and methyl cellulose. The formulations can additionally include lubricating agents such as talc, magnesium stearate and mineral oil, wetting agents, emulsifying and suspending agents, preserving agents such as methyl and propylhydroxybenzoates, sweetening agents or flavoring agents. The compositions of the invention may be formulated so as to provide quick, sustained or delayed release of the active ingredient after administration to the patient by employing procedures well known in the art.

The compositions are preferably formulated in a unit dosage form, each dosage containing from about 0.5 to about 50 mg, more usually about 1 to about 10 mg of the active ingredient. The term "unit dosage form" refers to physically discrete units suitable as unitary dosages for human subjects and other mammals, each unit containing a predetermined quantity of active material calculated to produce the desired therapeutic effect, in association with a suitable pharmaceutical excipient.

The following examples are illustrative only and are not intended to limit the scope of the invention in any way.

FORMULATION 1

Hard gelatin capsules are prepared using the following ingredients:

    ______________________________________                                                              Quantity                                                                       (mg/capsule)                                              ______________________________________                                         (+)-6-(3-isoxazolyl)-4-(di-n-                                                                         25                                                      propylamino)-1,3,4,5-tetrahydrobenz-                                           [cd]indole                                                                     Starch, dried          425                                                     Magnesium stearate     10                                                      Total                  460      mg                                             ______________________________________                                    

The above ingredients are mixed and filled into hard gelatin capsules in 460 mg quantities.

FORMULATION 2

A tablet formula is prepared using the ingredients below:

    ______________________________________                                                           Quantity (mg/tablet)                                         ______________________________________                                         (±)-6-[3-(5-aminothiazolyl)]-4-                                                                 25                                                         (di-n-propylamino)-1,3,4,5-tetra-                                              hydrobenz[cd]indole                                                            Cellulose, microcrystalline                                                                        625                                                        Colloidal Silicon dioxide                                                                          10                                                         Stearic acid         5                                                         ______________________________________                                    

The components are blended and compressed to form tablets each weighing 665 mg.

FORMULATION 3

A dry powder inhaler formulation is prepared containing the following components:

    ______________________________________                                                             Weight %                                                   ______________________________________                                         (±)-6-(5-isoxazolyl)-4-(di-n-                                                                      5                                                       propylamino)-1,3,4,5-tetrahydrobenz-                                           [cd]indole                                                                     Lactose               95                                                       ______________________________________                                    

The active compound is mixed with the lactose and the mixture added to a dry powder inhaling appliance.

FORMULATION 4

Tablets each containing 60 mg of active ingredients are made up as follows:

    ______________________________________                                         (+)-6-(2-pyrazolyl)-4-(di-n-                                                                          60       mg                                             propylamino)-1,3,4,5-tetrahydrobenz-                                           [cd]indole                                                                     Starch                 45       mg                                             Microcrystalline cellulose                                                                            35       mg                                             Polyvinylpyrrolidone (as 10%                                                                          4        mg                                             solution in water)                                                             Sodium carboxymethyl starch                                                                           4.5      mg                                             Magnesium stearate     0.5      mg                                             Talc                   1        mg                                             Total                  150      mg                                             ______________________________________                                    

The active ingredient, starch and cellulose are passed through a No. 20 mesh U.S. sieve and mixed thoroughly. The solution of polyvinylpyrrolidone is mixed with the resultant powders which are then passed through a No. 4 mesh U.S. sieve. The granules so produced are dried at 50°-60° C. and passed through a No. 16 mesh U.S. sieve. The sodium carboxymethyl starch, magnesium stearate and talc, previously passed through a No. 30 mesh U.S. sieve, are then added to the granules which, after mixing, are compressed on a tablet machine to yield tablets each weighing 150 mg.

FORMULATION 5

Capsules each containing 20 mg of medicament

    ______________________________________                                         (±)-6-(5-oxadiazolyl)-4-(di-                                                                       20       mg                                             methylamino)-1,3,4,5-tetrahydrobenz-                                           [cd]indole                                                                     Starch                 169      mg                                             Magnesium stearate     1        mg                                             Total                  190      mg                                             ______________________________________                                    

The active ingredient, cellulose, starch and magnesium stearate are blended, passed through a No. 20 mesh U.S. sieve, and filled into hard gelatin capsules in 190 mg quantities.

FORMULATION 6

Suppositories each containing 225 mg of active ingredient are made as follows:

    ______________________________________                                         (+)-6-(4-pyridinyl)-4-(di-n-propyl-                                                                  225       mg                                             amino)-1,3,4,5-tetrahydrobenz[cd]-                                             indole                                                                         Saturated fatty acid glycerides to                                                                   2,000     mg                                             ______________________________________                                    

The active ingredient is passed through a No. 60 mesh U.S. sieve and suspended in the saturated fatty acid glycerides previously melted using the minimum heat necessary. The mixture is then poured into a suppository mold of nominal 2 g capacity and allowed to cool.

FORMULATION 7

Suspensions each containing 50 mg of medicament per 5 ml dose are made as follows:

    ______________________________________                                         (±)-6-(2-thiazolyl)-4-(di-n-                                                                       50        mg                                            propylamino)-1,3,4,5-tetrahydrobenz-                                           [cd]indole                                                                     Xanthan Gum            4         mg                                            Sodium carboxymethyl cellulose (11%)                                           Microcrystalline Cellulose (89%)                                                                      50        mg                                            Sucrose                1.75      g                                             Sodium Benzoate        10        mg                                            Flavor                 q.v.                                                    Color                  q.v.                                                    Purified water to      5         l                                             ______________________________________                                    

The medicament, sucrose and xanthan gum are blended, passed through a No. 10 mesh U.S. sieve, and then mixed with a previously made solution of the microcrystalline cellulose and sodium carboxymethylcellulose in water. The sodium benzoate, flavor and color are diluted with some of the water and added with a stirring. Sufficient water is then added to produce the required volume.

FORMULATION 8

Capsules each containing 50 mg of medicament are made as follows:

    ______________________________________                                         (+)-6-(5-isoxazolyl)-4-(di-methyl-                                                                   50        mg                                             amino)-1,3,4,5-tetrahydrobenz[cd]-                                             indole                                                                         Starch                507       mg                                             Magnesium stearate    3         mg                                             Total                 560       mg                                             ______________________________________                                    

The active ingredient, cellulose, starch and magnesium stearate are blended, passed through a No. 20 mesh U.S. sieve, and filled into hard gelatin capsules. 

We claim:
 1. We claim compounds of the formula ##STR16## wherein R¹ is hydrogen, C₁ -C₄ alkyl, C₃ -C₄ alkenyl, cyclopropylmethyl, phenylsubstituted C₁ -C₄ alkyl, --(CH₂)_(n) S(C₁ -C₄ alkyl), --C(O)R⁴ --(CH₂)_(n) C(O)NR⁵ R⁶,R² is hydrogen, C₁ -C₄ alkyl, cyclopropylmethyl or C₃ -C₄ alkenyl; R³ is hydrogen, C₁ -C₄ alkyl or an amino protecting group; n is 1-4; R⁴ is hydrogen, C₁ -C₄ alkyl, C₁ -C₄ haloalkyl, C₁ -C₄ alkoxy or phenyl; R⁵ and R⁶ are independently hydrogen, a C₁ -C₄ alkyl, or a C₅ -C₈ cycloalkyl with the proviso that when one of R⁵ or R⁶ is a cycloalkyl the other is hydrogen; HET is a pyridinyl ring; or pharmaceutically acceptable salts thereof.
 2. The compounds of claim 1 wherein R¹ and R² are independently a C₁ -C₃ alkyl or a pharmaceutically acceptable salt thereof.
 3. The compounds of claim 1 wherein R³ is hydrogen or a pharmaceutically acceptable salt thereof.
 4. The compounds of claim 3 wherein R¹ and R² are independently a C₁ -C₃ alkyl or a pharmaceutically acceptable salt thereof.
 5. The compounds of claim 1 wherein R¹ is --(CH₂)_(n) C(O)NR⁵ R⁶ wherein n is 2, R⁵ is hydrogen, R⁶ is cyclohexyl, R² is a C₁ -C₃ alkyl, and R³ is hydrogen or a C₁ -C₄ alkyl or a pharmaceutically acceptable salt thereof.
 6. A substantially pure stereoisomer of a compound of claim 1 or a pharmaceutically acceptable salt thereof.
 7. A pharmaceutical formulation comprising a compound of claim 1 or a pharmaceutically acceptable salt thereof in combination with a pharmaceutically acceptable excipient therefor.
 8. A method for treating a mammal with a serotonin related disorder which comprises administering an effective amount of a compound of claim 1 or a pharmaceutically acceptable salt thereof.
 9. The method of claim 8 wherein said disorder is selected from the group consisting of anxiety, depression, gastric acid secretion, hypertension, nausea, sexual dysfunction, cognitive dysfunction, senile dementia, and consumptive disorders.
 10. The method of claim 9 wherein said consumptive disorders are selected from the group consisting of appetite, disorders, alcoholism and smoking.
 11. A method for treating a disease state which requires alternation of 5-HT receptor function said method comprising administering an effective compound of a compound of claim 1 or a pharmaceutically acceptable salt thereof.
 12. The method of claim 11 wherein said 5-HT receptor is 5HT_(1A) a receptor.
 13. The method of claim 11 wherein said 5-HT receptor is 5HT_(1D) a receptor.
 14. A compound of claim 1, said compound being 6-(4-pyridinyl)-4-(di-n-propylamino)-1,3,4,5-tetrahydrobenz[cd]indole or a pharmaceutically acceptable salt thereof. 